New fecal test for non-invasive Helicobacter pylori detection: A diagnostic accuracy study

Abstract

AIMTo assess the diagnostic accuracy of a new fecal test for detecting Helicobacter pylori (H. pylori), using13C-urea breath test as the reference standard, and explore bacterial antibiotic resistance.METHODSWe conducted a prospective two-center diagnostic test accuracy study. We enrolled consecutive people≥ 18 years without previous diagnosis of H. pylori infection, referred for dyspepsia between February and October 2017. At enrollment, all participants underwent 13C-urea breath test. Participants aged over 50 years were scheduled to undergo upper endoscopy with histology. Participants collected stool samples 1-3 d after enrollment for a new fecal investigation (THD fecal test). The detection of bacterial 23S rRNA subunit gene indicated H. pylori infection. We also used the index diagnostic test to examine mutations conferring resistance to clarithromycin and levofloxacin. Independent investigators analyzed index test and reference test standard results blinded to the other test findings. We estimated sensitivity, specificity, positive (PPV) and negative (NPV) predictive value, diagnostic accuracy, positive and negative likelihood ratio (LR), together with 95% confidence intervals (CI).RESULTSWe enrolled 294 consecutive participants (age: Median 37.0 years, IQR: 29.0-46.0 years; men: 39.8%). Ninety-five (32.3%) participants had a positive13C-urea breath test. Twenty-three (7.8%) participants underwent upper endoscopy with histology, with a full concordance between 13C-urea breath test and histology in detecting H. pylori infection. Four (1.4%) out of the 294 participants withdrew from the study after the enrollment visit and did not undergo THD fecal testing. In the 290 participants who completed the study, the THD fecal test sensitivity was 90.2% (CI: 84.2%-96.3%), specificity 98.5% (CI:96.8%-100%), PPV 96.5% (CI: 92.6%-100%), NPV 95.6% (CI: 92.8%-98.4%), accuracy 95.9% (CI: 93.6%-98.2%), positive LR 59.5(CI: 19.3-183.4), negative LR 0.10 (CI: 0.05-0.18). Out of 83 infected participants identified with the THD fecal test, 34 (41.0%) had bacterial genotypic changes consistent with antibiotic-resistant H. pylori infection. Of these, 27 (32.5%) had bacterial strains resistant to clarithromycin, 3 (3.6%) to levofloxacin, and 4 (4.8%) to both antibiotics.CONCLUSIONThe THD fecal test has high performance for the non-invasive diagnosis of H. pylori infection while additionally enabling the assessment of bacterial antibiotic resistances.

Helicobacter pylori Primary and Secondary Genotypic Resistance to Clarithromycin and Levofloxacin Detection in Stools: A 4-Year Scenario in Southern Italy

“…In addition, it may represent a pioneering large-scale attempt to apply noninvasive detection of antibiotic resistance in stools, which may become a relevant procedure in clinical practice. The feasibility and the agreement with standard methods for antibiotic resistance detection have already been proven in previous studies [ 17 , 18 ]. In addition, to the best of our knowledge, this is the first report investigating gyrA mutation for levofloxacin resistance to H. pylori in stools.…”

“…Moreover, different groups have already set up systems to detect point mutations in stools. In this setting, the THD fecal test has shown sensitivity and specificity above 90% [ 17 ] and a 100% concordance for the point mutations conferring resistance to clarithromycin between stools and gastric biopsy samples [ 18 ]. While a recent meta-analysis [ 19 ] identified the bacterial 23S ribosomal RNA subunit gene as the most accurate marker for diagnosis of infection using molecular tests on stool samples, with 82% sensitivity and 99% specificity, there are no data about the detection of gyrA mutations in stools.…”

Review: Diagnosis of Helicobacter pylori infection

“…38 An indirect approach for a non-invasive, molecular diagnosis of The test allows for the detection of H. pylori-specific sequences including mutations associated with clarithromycin and levofloxacin resistance.…”

“…However, no reference test was used for the assessment of resistance to the two antibiotics. 38 An indirect approach for a non-invasive, molecular diagnosis of…”

The Puzzle of Coccoid Forms of Helicobacter pylori: Beyond Basic Science

“…In the previous experience of our group, H. pylori DNA sequences were found in three out of fifty histology-negative cases, thus suggesting that RT-PCR may be a key tool for refining bacterial detection by both clarifying the diagnosis in doubtful cases and guiding a successful therapeutic regimen by detecting antibiotic resistances [86]. After this preliminary experience, a noninvasive molecular test with high sensitivity and specificity (THD fecal test) was developed to detect DNA-specific sequences and point mutations in the stools of patients [85,87].…”